Physicochemical and Biological Evaluation of Doxycycline-Loaded Polycaprolactone Nanofibers Produced by Solution Blow Spinning for Bone Regeneration

Purpose To develop an ISO-guided in vitro evaluation solution of blow-spun polycaprolactone (PCL) nanofibrous mats loaded with doxycycline (DOX) as bioactive scaffolds for bone regeneration and localized antibiotic delivery. Methods PCL solutions (12% w/v, glacial acetic acid) were processed by solution blow spinning with 2, 4, and 8% (w/w, relative to PCL mass). Solution viscosity and surface tension were measured; SEM and image analysis assessed fiber morphology and diameter; FTIR verified chemical composition. Cytotoxicity of material extracts was tested in L-929 fibroblasts using the MTT assay according to ISO 10993-5:2009. Osteogenic bioactivity was assessed in SAOS-2 cultures by Alizarin Red staining and SEM–EDS analysis of calcium and phosphate deposition. Results DOX reduced solution viscosity without markedly altering surface tension and did not prevent fiber formation, although higher DOX concentrations increased bead occurrence. FTIR spectra were consistent with DOX incorporation, without apparent degradation. Extracts from 2% and 4% DOX mats met the ISO 10993-5 viability acceptance criterion, whereas 8% DOX fell below this threshold. All groups supported mineralized matrix formation, with qualitatively stronger calcium deposition on 4% DOX mats than on drug-free or 8% DOX mats. Conclusion Solution blow-spun PCL–DOX nanofibers, particularly at 4% DOX, provide an ISO-compliant in vitro evidence base for further development as bioactive scaffolds combining structural support and controlled antibiotic delivery. Follow-up work should quantify release kinetics and test performance in more biomimetic, advanced in vitro models.